Hydraulic apparatus



2 Sheets-Sheet 1 J. H. JOHNSON HYDRAULIC APPARATUS &

April 12, 1966 Filed April 6, 1965 I N VEN TOR. JOH/Y ll. dour/son 6% ZaArTo /vey April 12, 1966 J. H. JOHNSON HYDRAULIC APPARATUS 2 Sheets-Sheet 2 Filed April 6, 1965 IN VEN TOR. Jon/v ll- JoH/Yso/v United States Patent 3,245,326 HYDRAULIC APPARATUS John H. Johnson, Jamestown, N.Y., assignor to 'I'RW Inc, a corporation of Ohio Filed Apr. 6, 1965, Ser. No. 445,969 6 Claims. (Cl. 92-139) This is a continuation-in-part of my copending application Serial No. 234,932, filed on November 2, 1962, and entitled Hydraulic Apparatus, which was forfeited on May 18, 1965.

This invention relates to hydraulic apparatus and particularly to hydraulic apparatus of the piston type.

Of particular interest is the actuation of the pistons of axial type pumps and motors and the sealing of the valve means between the rotary and stationary parts interchanging fluid with the bores containing the pistons. Although the following description of the invention is in connection with hydraulic pumps and motors, features of the invention are also applicable to other types of hydraulic devices.

An object of the invention is to provide means for reciprocally actuating a hydraulic piston without applying side loads on the walls of the bore in which the piston travels.

Another object of the invention is to provide a hydraulic pump or motor that has a low level of noise and vibration.

Another object of the invention is to balance the axial fluid pressures on a cylinder block receiving fluid at one end and discharging at the other.

Another object of the invention is to provide a hydraulic type of cam follower.

Other and further objects of the invention will be apparent from the following description taken in connection with the drawings in which:

FIG. 1 is a sectional view of the pump taken through an inlet passage and a discharge passage;

FIG. 2 is a sectional view of the pump taken along lines 2-2 of FIG. 1;

FIG. 3 is a comparative sectional view of the intake and the cylinder block 11 and a stationary casing 12 supporting inlet and outlet housings 13 and '14, respectively, which in turn rotatably support multi-lobe earns 15 and 1-6.

The casing 12 has a main supporting cylindrical memher 17 with pedestals 18. The upper end is open and has a housing 19 for supporting the cam adjusting means 21, 22.

The cylinder block 11 has nine axial passages 23 extending lengthwise from the end sealing surface 24 to the end sealing surface 25 for supplying and receiving hydraulic fluid from nine cylindrical bores 26 with pistons 27 and 28, respectively. The pistons 27 and 28 are driven by the cam followers 31, 32, respectively, mounted in recesses 33, 34 as axial extensions of the bores 26. The cam followers 31, 32 engage the cams 15 and 16 which have five lobes apiece for producing five reciprocations of the pistons on each rotation of the cylinder block 11.

The inlet housing 13 fixedly supports a valve plate or block 29 which has five passages 35 for receiving fluid from the inlet annulus 36 and passing the fluid to the cylinder block on a passage 35 registering with a passage 23 in the cylinder block. The valve plate 29 has a sealing surface 37 extending around the axis of the pump and encompassing the passages 35. The sealing surface 24 'bears against the surface 37 to seal the transfer of fluid.

At the discharge side high fluid pressures are created by the action of the pistons. The outlet housing -14 supports a valve block 38 which is coupled to the cylinder block 11 by means of the floating valve plate 39 and the tubular members 40. The valve block 38 has five passages 41 continuously coupled to the annulus 42 in the outlet housing 14. The valve block 38 and valve plate 39 have recesses for receiving the tubular members 40 with spaces 43, 44 betwen the ends of the tubular mem- [hers and the valve block and valve plates. The valve plate has five orifices 45 for receiving fluid from the cylinder block. The orifices 45 are equally and circumferentially spaced around the axis. The orifices 45 are not aligned with the inlet passages 35, but are circumferentially offset so as to project midway between the passages 35. A sealing surface 46 on the valve plate engages the surface 25 on the cylinder block to seal the transfer of fluid. The sealing pressures are created by the fluid in the annular spaces 43 and 44 between the ends of the tubular members and the valve Iblock and valve plate. Seals 47 are provided on the ends of the tubular members.

In order to balance the fluid pressures on the ends of the cylinder block, in addition to the inlet and outlet passages the inlet valve block and the valve plate have blind recesses 48, 49. The five recesses 49 in the valve plate correspond and are aligned with the inlet passages 35 and the five blind recesses 48 in the inlet valve block correspond and are aligned with the outlet passages or orifices 45.

The inlet and outlet annuli 36, 42 provide a circumferential uniform fluid pressure. On the outlet side of the pump this uniform pressure is applied at five equally spaced points by the chambers 43, 44 to the sealing surfaces 35, 46. This pressure also presses the cylinder block sealing surface 24 against the sealing surface 37 of the inlet valve block.

A separating force occurs between the cylinder block 11 and the inlet valve block 29 and between the valve plate 39 and the cylinder block 11 when the passages 23 in the cylinder block overlap with passages in the inlet valve block or outlet valve plate. When either passage 35 or 45 overlaps with the passage 23, the cylinder block is subjected to fluid pressure on the surface overlapping or covering the passage 23. In order to balance these forces on the cylinder block, the blind recesses 48 and 49 are provided. These recesses 48, 49 are of the same crosssectional size and shape as the respective passages 35 and 45. Thus when passage 35 is in overlapping relation with the passage 23, the corresponding recess 48 which is longitudinally aligned with the corresponding passage 35 is also in overlapping relation. A portion of the end of the cylinder block thus overlaps with the recess 48 and fluid pressure is applied to the recess 48 through the non-overlapping portion to apply a balancing force on the end of the cylinder block. The blind recess 49 and passage 35 correspondingly cooperate to balance the forces on the cylinder block. Since fluid pressure is always present in the passages 35 and 45 from the respective annuli 36 and 42, the spacing of the cylinder block passages 23 is equal to or slightly less than the width of a blind recess. Thus each of the recesses is in communication with a passage 23 to receive fluid pressure for balancing the fluid pressures applied by the passages 45 and 35. Identical pressure distributions are maintained on both sides of the cylinder block.

The pressure developed in the chambers 43, 44 will prevail in maintaining a uniform pressure.

The cam followers 31, 32 are identical and a description of one will suflice for all. In FIG. 4 the cam follower 31 comprises a cylindrical member 50 and a ball 51 seated therein. The end of the piston 27 fitting in the recess 52 has a circumferential groove 53 complementary to the groove 54 in the cylindrical member. Bearing balls 55 fit in the two grooves to lock the piston and cylindrical member together. The overlapping of the cam follower and the piston by the fitting of the piston into a recess in the cam follower and the coupling of these two members by the grooves and balls forms a coupling means that permits the interchange of forces permitting the coupling means to be non-aligned with the piston or angulated while avoiding the application of side loads to the piston. The grooves may be filled with the balls in any conventional manner, such as through an orifice 95 in the side with a plug 96.

The cylindrical member has curved seating surfaces 56 forming a seat for the ball. The surfaces are provided with fluid under pressure by means of the annular channel 57 connected to the passage 23 by the duct 58. Crossed bores 59 and the orifice 6t) supply the fluid from the channel. Thus as the piston increases the fluid pressure on the compression stroke, the fluid pressure on the seating surfaces is also increased. Thus the ball is hydrostatically supported with the pressure in the hydrostatic bearing always proportional to the piston pressure loadmg.

The forces on the cam bearing ball 51 are illustrated in FIG. 5. A force F is applied by the cam follower 31 against the cam bearing ball 51 to seat the ball in the cam follower. The fluid pressure applied through the duct 60 is applied on the surface S which has a diameter D corresponding to the diameter of the recess 72. The fluid pressure drops across the seating surface 56 to a zero pressure or to the case pressure at diameter D The diameters D and D are set so that the integral of the curve of pressure versus diameter gives a separating force slightly less than F The amount of over force depends upon the fluid being pumped and is of the order of The amount of over force is set to minimize the fluid film thickness on the seat 56 in order to minimize leakage without metal to metal contact. In calculating the over force the slope of the cam must be taken into consideration. The force R applied to the bearing ball is larger than the pressure force F since the force R is at an angle to the axis. The resulting force R may be represented by component forces F2 and Ft. The component F is axial and Ft is normal to the axis of the cam follower. The moment of force F about any point on the seating surface defined by D and D must equal or exceed the sum of the moments of Pt and the fluid separating force. As previously stated, this latter force is slightly less than the force F Variations in loading moment due to variations in cam angle must be kept within the limit of load support capability of the fluid film.

For the return of the piston on the suction stroke, hydraulic pressure is applied to the piston end of the cylindrical member. A circumferentially extending space 61 is formed between the sleeve 63 and the cylinder block to connect the recesses or chambers in which the cam followers are positioned. Each chamber is connected by a duct 62 to the annular space. The entire space is filled with fluid and the pistons moving on the compression stroke create pressure which forces the cam follower against the cam on a suction stroke. The total volume of these chambers is essentially constant since pistons are moving out at the same rate they are moving in. The chambers are kept supplied with fluid by leakage past the working pistons. Excessive pressure build-up in these chambers is prevented by a relief valve 75 in the circumferentially extending space 61.

As previously mentioned, there are nine passages 23 and main bores 26 in the cylinder block and five lobes on QEL Ih .cam, Each lobe has a corresponding pair of inlet and outlet ports. Thus each pair of opposing pistons makes five strokes on each revolution and nine pairs provide a total of forty-five strokes per revolution. Since there are an odd number of pairs of pistons, each pair is at a different portion of a respective lobe. This provides for a more uniform pressure, since each pair delivers a maximum pressure at different times. The cams 15 and 16 are rotatably mounted on bearings and are rotated circumferentially to vary the output of the pump. Arcuate racks 65, 66 are provided on earns 15 and 16 which are engaged by worm gears 67, 68mounted on the rotatable shafts 69, 70. The thread of worm gear 67 is Opposite to that of worm gear 68 in order to rotate the cams in opposite directions and vary the axial relationship of the cam lobes. The shafts are coupled by a chain 71. The pump capacity is zero when the lobes of one cam match the recesses of the other cam causing the pistons to move in the same direction.

The axial length of the inlet and outlet annuli 3'6, 42 permits the pump to be adapted to the handling of large quantities of fluid while maintaining the sealing surfaces and the areas producing the pressures on the valve plate 39 within reasonable dimensions. The ports and valve plate balance is independent of the design of the positions. Thus the size of the port openings and fluid velocities therethrough are generally independent from the size and stroke of the piston.

Further, the valve plate sealing pressures are relatively low. The symmetrical distribution of the outlet ports and the continuous annular chamber formed by the outlet annulus results in a substantially symmetrical pressure distribution. The symmetry of the sealing pressure also permits a reduction in the over pressure required in order to maintain the proper sealing pressure at all times.

The oppositely positioned blind recesses for each inlet and outlet port balance the separating force leaving the control of the forces on the cylinder block with the valve plate.

The balancing of the separating forces and the symmetrical distribution of the sealing forces reduce the friction between the inlet housing and the valve plate. The hydrostatic support of the balls on the cam followers and the use of a rolling contact reduce the friction and torque loss to a minimum. The reaction cams and the ball followers have pure rolling contact to keep frictional losses to a minimum. The torque is carried through the cam followers with the line of action of the reaction forces located within the cam follower to provide in creased stability of operation. The pressure lubrication and 'low unit load maintain the friction of the cam followers to a low amount.

The earns 15 and 16 are rotatably mounted on the ball bearings 76, 77, respectively, to permit the easy adjustment of the cams. The pistons 27, 28 fit tightly in the bores 26 to form seals with the walls of the bore so that the pistons are firmly held against lateral movement. The ball coupling of the pistons to the cam followers 31, 32 permits adjustment of the pistons so as to eliminate :side loads of the pistons against the walls. The pistons are withdrawn from the bores by the cam followers acting through the balls coupling the cam followers and the pistons. On the compression stroke the rounded seating ends 73, 74 on the piston engage the bottom wall of the recess 52 for the transmission of force between the pistons and the cam followers. The rounded seating ends permit a rocking action between the cam followers and the pistons to further eliminate side loads. Thus a firm coupling is provided between the cam followers and the pistons.

In FIG. 6 another embodiment of the interconnection of a piston and a coupling rod 81 is illustrated. The piston 80 is fitted in the bore 82 of the cylinder block 83 and the coupling rod 81 fits in a guide 84 fastened to the cylinder block 83 by bolts 85. The piston 80 is larger than the coupling rod 81 and has a recess 86 formed'by a cylindrical wall 87 having a groove 88. The recess also has a flat bottom wall 89. The coupling rod 81 has a groove 90 complementary to the groove 88 to form a channel in which the bearing balls 91 are fitted to couple the rod and piston together. The rod has a rounded end 92 bearing against the flat bottom 89 for transmission of compression forces between the piston 80 and the coupling rod 81. The surfaces 89 and 92 are related to permit a rocking action, and other configurations of these two surfaces may be used to secure the same result. The guide 84 may be secured to other portions of the stationary structure than the cylinder block 83. As in the other embodiment, this coupling permits angulation between the piston 80 and the coupling rod 81 without applying side loads to the piston.

On transmission of force between the cam followers and the cams, the force is transmitted to the casing through the outer races of the hearings to the balls to the inner races which are seated on the inlet and discharge blocks 29, 38.

The hydrostatica-lly supported bearing balls provide a substantially frictionless transfer of force between the cams and pistons and the cam follower return pressure produces a quiet retention of the bearing balls on the cams. The bearing balls are thus continuously in contact with the cams. The rolling contact of the bearing ball with the cam maintains the line of action of the reaction forces well within the cam follower geometry to provide stable operation.

The provision of two sets of multiple pistons reciprocating many times during the single rotation of the cylinder block enhances the smooth operation and produces an essentially constant pump pressure with the pulsations at a minimum. The annulus supply and discharge 36 and 42 permit the capacity of the pump to be increased by increasing the length of these annuluses while maintaining the inlet and discharge orifices at an operatively acceptable size. The size of these openings is independent of .the piston diameter and stroke, thus permitting the control of fluid velocities in keeping with the motion of the piston elements.

The blind recesses balance the separating forces so that the pressure on the valve plate 39 maintains a continuous and constant pressure on the cylinder block and holds the cylinder block continuously against the inlet block. This balancing of pressure permits a reducing in the over pressure required to insure proper sealing of the inlet and outlet ports and also provides a uniform distribution of the wear on the sealing surfaces. This uniform pressure also avoids the variation in the relationship of the sealing surfaces with a resultant reduction in noise.

The coupling between a piston and a respective cam follower provides for adjustment between-these members which eliminates side loads while permitting the cam followers to vary in relation to the pistons. This structure has other applications than to hydraulic pumps and motors; for example, hydraulic jacks may use this coupling to provide a tight seal between the cylinder and piston.

Other adaptations and modifications of the embodiments of the inventions may be made without departing from the scope thereof as set forth in the appended claims.

I claim:

1. A hydraulic apparatus comprising a cylinder block with a bore, piston means slideably and tightly fitting in said bore and coupling means for interchanging forces with said piston means, one of said means having a recess for receiving the end of said other means for positioning said piston means and said coupling means in overlapping relation and said means with the recess having a bottom engaged by the end of the other means for transmitting forces therebetween, said coupling means and said piston means having complementary grooves to form a circular passage, a plurality of balls in said passage to flexibly couple said coupling means and said piston means to permit non-alignment and angulation between said coupling means and said piston means without applying side loads between the piston and the cylinder block.

2. A hydraulic apparatus comprising a cylinder block with a bore, a piston slideably and tightly fitting in said bore, coupling means for interchanging forces with said piston, said coupling means having a recess for receiving the end of said piston in overlapping relation and having a bottom engaged by the end of the piston for transmitting forces therebetween, said coupling means and said piston having complementary grooves to form a circular passage, a plurality of balls in said passage to flexibly couple said means and said piston to permit separate alignment and angulation of said means and said piston.

3. A hydraulic apparatus comprising a cylinder block with a bore, a piston slideably and tightly fitting in said bore, coupling means for interchanging forces with said piston, said piston having a recess for receiving the end of said coupling means in overlapping relation and having a bottom engaged by the end of the coupling means for transmission of forces therebetween, said coupling means and said piston having complementary grooves to form a circular passage, a plurality of balls in said passage to flexibly couple said means and said piston to permit angulation of said means and said piston.

4. A hydraulic apparatus as set forth in claim 1 wherein said bottom and said end are related to permit a rocking action therebetween.

5. A hydraulic apparatus comprising a cylinder block with a bore, guide means, a piston slideably :and tightly fitting in said bore, a force interchanging member slideably mounted in said guide means, said piston and said member having surfaces in butting relationship generally normal to the force transmitted therebetween, said piston and member having portions overlapping with a single set of complementary grooves and balls therein to form the sole means flexibly interconnecting said member and said piston to permit separate alignment of said piston and said member.

6. A hydraulic apparatus comprising a cylinder block with a bore, piston means slideably and tightly fitting in said bore and coupling means for interchanging forces with said piston means, one of said means having a recess for receiving the end of said other means for positioning said piston means and said coupling means in overlapping relation, said piston means and said coupling means having surfaces in butting relationship generally normal to the forces transmitted therebetween, said coupling means and said piston means having complementary grooves to form a circular passage, a plurality of balls in said passage to flexibly couple said coupling means and said piston means to permit non-alignment and angulation between said coupling means and said piston means without ippllying side "loads between the piston and the cylinder References Cited by the Examiner UNITED STATES PATENTS 2,585,408 2/1952 Roberson 92116 SAMUEL LEVINE, Primary Examiner. IRWIN C. COHEN, Assistant Examiner. 

1. A HYDRAULIC APPARATUS COMPRISING A CYLINDER BLOCK WITH A BORE, PISTON MEANS SLIDEABLY AND TIGHTLY FITTING IN SAID BORE AND COUPLING MEANS FOR INTERCHANGING FORCES WITH SAID PISTON MEANS, ONE OF SAID MEANS HAVING A RECESS FOR RECEIVING THE END OF SAID OTHER MEANS FOR POSITIONING SAID PISTON MEANS AND SAID COUPLING MEANS IN OVERLAPPING RELATION AND SAID MEANS WITH THE RECESS HAVING A BOTTOM ENGAGED BY THE END OF THE OTHER MEANS FOR TRANSMITTING FORCES THEREBETWEEN, SAID COUPLING MEANS AND SAID PISTON MEANS HAVING COMPLEMENTARY GROOVES TO FORM A CIRCULAR PASSAGE, A PLURALITY OF BALLS IN SAID PASSAGE TO FLEXIBLY COUPLE SAID COUPLING MEANS AND SAID PISTON MEANS TO PERMIT NON-ALIGNMENT AND ANGULATION BETWEEN SAID COUPLING MEANS AND SAID PISTON MEANS WITHOUT APPLYING SIDE LOADS BETWEEN THE PISTON AND THE CYLINDER BLOCK. 